[ltt-dev] Trace "destroy" hangs, lttd keeps running

Mathieu Desnoyers mathieu.desnoyers at polymtl.ca
Fri Nov 20 09:37:12 EST 2009

* Ashwin Tanugula (ashwin.tanugula at broadcom.com) wrote:
> > >
> > > I continued my testing using "return 1;" to reproduce the errors with 
> > > the viewer, so that I can send you my trace data.
> > >
> > OK. Then let's revert to the previous lttng assumption: synchronized TSCs across MIPS cores. Does that work for you ? (I see that you configured your kernel with support for 2 CPUs. Do you have an SMP board ?)
> Yes, I am running the kernel ins SMP mode.
> In UP mode I don't see the UNSYNCHRONIZED TSC problem (which I guess
> is obvious)

Hi Ashwin,

Then you'll have to try disabling everything that can try to scale the
CPU frequency when you boot your system, and see if it works better.

Support non-synchronized TSCs on MIPS will have to wait until

a) This feature gets requested as a contract.
b) I can get my hands on a SMP mips32 board with such frequency scaling.

So for now let's focus on just making sure LTTng works when all
frequency scaling features are disabled at boot time.



> Thanks,
> Ashwin
> > MIPS assume synchronized TSC
> > Code for non-synchronized TSC support was broken (at least for MIPS32). I suspect the spinlock did not do well with NMIs or something like this. Revert to assuming synchronized TSCs across cores until someone send me a MIPS board to play with.

Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

More information about the lttng-dev mailing list